bbrown2828
150cc
Morning [MENTION=3239]clarkj[/MENTION]
bbrown2828
150cc
Hopefully it's before spring [MENTION=3239]clarkj[/MENTION]. Maybe we can get some guys from. Redwing to meet us at Sikeston on weekend and fly. @timp [MENTION=2470]RedwingRC[/MENTION]
Aeroplayin
70cc twin V2
I hear ya. For me, it's just a matter or convenience and necessity. When I just want to break away and fly, electric always seems more convenient. If dead sticks were all about tuning, there'd be no problem. I wish I was as talented as you are, and were able to avoid all dead sticks. I had one on takeoff at 30 feet with no runway or altitude because the fuel line slipped off a tube inside the tank on a 50cc I bought used. Not much damage actually, but a constant reminder of the many things that need to be inspected.
For most guys flying 3D, it's all about the weight. For me, I don't need to fly around at full speed for 10 minutes, never do, and prefer enough power, torque, and thrust, to move from a full stall maneuver back to operational speed quickly, so I like electric power. But the heavier, beefed up planes coming along recently favor gas engines. I look for the wing cube loading and power loading I want, and go with the best option, looking at electric first since I now have all the accessories and a boat load of batteries. For me, that's 270 Watts per pound (Watts-in) for electric, which is about the same as 0.30 HP per pound for gas, which is the same as about 225 Watts-out per pound.
Up to 25 pounds, the 6800 Watts-in that are needed means 155A on 12S. With a 5200mAh battery capacity, which is close to a weight trade-off with the takeoff weight of a gas setup with about the same power, flying around at WOT will mean 1.6 minutes of flight time (37C discharge). At a normal 33 to 40 percent power for 3D guys, that's still only 4 to 5 minutes. To go to 6600mAh, I would get 6.2 minutes, so that's acceptable, but the added 1400mAh capacity means about a full pound in added weight. So I now have to readdress my power to weight.
I don't mind flying for 6 minutes, but I do mind being limited to 4.
It also looks like planes are not going to be getting lighter any time soon, probably because no brand wants to see videos of their planes folding up in the air, so the trend is toward beefier airframes considering how guys are pounding these planes now. Try a big-sky, full-speed, split-S, into a Chrankshaft at the bottom of the half-loop a few times each flight, and see how many planes survive that for 500 flights.
The new power densities will probably help up to 5500W setups, but we still have to see what the weights are. Density is mass per volume, so I suspect heavier with the same size package.
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alawson999
70cc twin V2
Mah per ounce
In electric vehicles it is a major discussion point, though measure in kwh per kg
In electric vehicles it is a major discussion point, though measure in kwh per kg
dribar
70cc twin V2
I'm still in the Betamax vs VHS battle....
Aeroplayin
70cc twin V2
My current rule of thumb, before things begin to change as the battery paradigm changes, is to use this simple formula for 40-50C batts...
Weight in grams = Number of Cells * mAh * 0.0265
So a 12 cell 5000mAh setup is 12*5000*0.0265 = approx. 1590g or 56 oz.
The 2x 6S Glacier, Sky Lipos, and Revos in the 40C to 45C range that I've weighed come in between 1542g and 1572g. The 70C TP's were 1632g, so higher discharge rates will require a little adjustment. Add about 10g for bullets, solder, and Velcro per battery, and we're in the same ballpark.
My 3300mAh Skys are 538g all up, so a 4 pack for 12S and 6600mAh is 2150g.
12S x 6600mAh x 0.0265 = 2099g.
Add 10g for bullets, solder, and Velcro, per battery, and it's really close.
I've tried some GForce E-lites that came in at 1496g for the 40C, and were smaller in size, but they didn't hold up quite as well as Revos and Skys which for the price seem to be a better deal IMO. Seems to qualify the argument about density too. I'd have no problem buying Glacier too. Always open to honest suggestions as well.
Weight in grams = Number of Cells * mAh * 0.0265
So a 12 cell 5000mAh setup is 12*5000*0.0265 = approx. 1590g or 56 oz.
The 2x 6S Glacier, Sky Lipos, and Revos in the 40C to 45C range that I've weighed come in between 1542g and 1572g. The 70C TP's were 1632g, so higher discharge rates will require a little adjustment. Add about 10g for bullets, solder, and Velcro per battery, and we're in the same ballpark.
My 3300mAh Skys are 538g all up, so a 4 pack for 12S and 6600mAh is 2150g.
12S x 6600mAh x 0.0265 = 2099g.
Add 10g for bullets, solder, and Velcro, per battery, and it's really close.
I've tried some GForce E-lites that came in at 1496g for the 40C, and were smaller in size, but they didn't hold up quite as well as Revos and Skys which for the price seem to be a better deal IMO. Seems to qualify the argument about density too. I'd have no problem buying Glacier too. Always open to honest suggestions as well.